This system uses automatic closed-head sprinklers that are attached to a piping system containing water. Water discharges immediately from those sprinklers opened by a fire. A flow of water through the valve sounds an alarm.
Wet pipe systems should not be used where freezing conditions are likely to damage piping. In systems using AFFF concentrate, the piping to the sprinkler heads can be pre-primed with foam solution to enable immediate effective foam discharge. AFFF solution in contact with steel pipe may gradually lose its fire effectiveness. Samples of this solution should be checked on an annual basis and replenished as needed. A test discharge connection is recommended downstream from the proportioner and should be located to fill a maximum portion of the sprinkler system piping. The test connection should be of sufficient size to meet the minimum flow rate for the particular proportioner. This type of system is the most reliable, simplest, and fastest responding of all closed-head sprinkler systems. Conversions of water systems to foam can usually be accomplished easily. (Local codes and regulations should be investigated prior to conversion.)
